A surge protective device (SPD), or surge protector, is an electrical device connected between a power source and a device being powered by the power source, which is configured to limit the voltage supplied to the powered device. In the event of a power surge, the SPD intercepts any voltage above a threshold safe/operating amount, known as the clamping voltage, and redirects the surge current. In industrial applications, SPDs are typically “shunt mode” protective devices, using electrical components (e.g., varistors) that let operating voltages pass through and become conductive above the clamping voltage. Once conductive, the components direct the transient voltage toward ground or otherwise away from the powered devices. These components are connected in parallel with the powered load so as not to disrupt normal current flow to the powered device. Some SPDs are sacrificial—the components can only withstand a limited number of surges before degrading to the point of failure, and must be replaceable.
Traditionally, SPDs are a separate component from any distribution or power blocks. The main function of the distribution or power block is to provide the power to the load; the main function of the SPD is to clamp the voltage as described. In a typical system, the SPD is electrically connected in parallel to the output side of the distribution or power block, and spaced away from the distribution block. This can result in impaired surge protection levels due to the extra wire lengths connecting the SPD to the protected equipment. An integrated SPD and distribution block would advantageously eliminate these excess wires while handling high current draws which are typical in industrial settings.